One of the major functions of the Center is to provide access to silicon substrate probes whose technology is being developed at the University of Michigan under the support of the NIH NCRR and the NIH Neural Prosthesis Program. At this time, only passive probes are available although it is anticipated that the chemical delivery probes and probes with on-chip electronics will one day be available. This was the first year in which 3-D arrays were provided to external users. Probes may be chosen from a catalog of available designs and, once they have shown that they can successfully apply the technology, experienced investigators may design probes customized to their individual application. Technical support in the areas of handling, testing and design is given over the phone or through email. Investigators are also referred to other internal or external investigators with similar interests and/or applications. In the past year, we provided at least 30 catalogs and 524 bonded probes to over 75 investigators throughout the U.S. and abroad. These probes came from the 22 wafers processed to completion in the fourth grant period from five different mask sets.